Combination jack



Jan. 16, I A Q MlDDLEMlSS COMBINATION JACK Filed May 51,'1929 um i \ IlyINVENTOR Patented Jan. 16, 1934 UNITED STATES PATENT OFFICE 1 Claim.

This invention relates to jacks of the mechanical type. The object ofthe invention is to produce a jack, eiiicient in operation by being bothsimple and geared, combining strength and light- 5 ness and alsocompactness in proportion to the lift. A further object of the inventionis a construction so designed that the jack is automatically protectedfrom lifting too far and disengaging the screw threads. These and otherfeatures will be apparent by a study of the accompanying drawing andspecifications.

Fig. 1 is a side elevation of the jack and cross sections.

Fig. 2 is a top View.

l5 Referring to these views, the part details are as follows: I is thebase; A is the screw bolted to the base; B is a sleeve or nut which isfitted to turn on part A; part C is a gear housing holding the gears andtted to allow relative rotation of part B but rising with it; part H ishinged at K and can be placed parallel to the axis of the screw orturned down as shown by the arrow. When the part H is out of the part C,part C and the part B which is locked to part C by the gearing may berotated by a bar placed in the bosses O. This makes it possible for thejack to operate as a simple screw jack. I-I is a pivotally mountedhousing restraining member. When part H engages part C, and suitableturning means are used on part F, the part B is revolved with thegearing with great power through the worm P, the worm wheel E which isintegral with gear D, gear D turns gear N which is integral with the nutB.

After part C has risen to a point such that it clears member H, furtherrotation of the part F will cause the entire gear train to rotate withrelation to the base I and the sleeve B. The sleeve B therefore fails torotate and becomes automatically inoperative as a geared jack, leaving asafe amount of threads engaged.

The top is shown as a spherical seat on the part B, Q is a washer, N isa spring and M is a screw.

Special attention is called to this construction, which makes itpossible to make the part B thick around the central hole and makes theoscillating top L tend to return to center.

Having thus clearly described my invention, what I claim is:

In a jack of the class described, the combination of a base with a screwattached, a threaded sleeve iitted to the screw, a gear housingsurrounding the sleeve, hollow projecting bosses on the housing, ageared drive comprising a worm wheel and a worm embraced by the housingand a restraining member coacting with a notch in the housing of limitedheight and pivotally attached to the base member.

AUSTIN O. MIDDLEMISS.

